1. Field of the Invention
The present invention relates to a maintenance method of liquid ejection head and a liquid ejection apparatus, and more particularly to maintenance technique of an ink ejection surface of a liquid ejection head of an inkjet type.
2. Description of the Related Art
Methods for printing high-quality images at high speed include: offset printing, relief printing, gravure printing methods, and the like. However, these methods are not suitable for printing small lots since they require time to manufacture the printing plate. On the other hand, an inkjet method has been proposed as a high-speed digital printing method, amidst increasing demands in recent years for digital printing having high-quality and high-speed characteristics. An inkjet method ejects ink from very fine holes (nozzles), and requires improvement in the accuracy of nozzle positions in order to achieve high image quality. In the related art, nozzles having a circular planar shape are manufactured by laser boring, or the like, but if nozzles are manufactured by this method, then variations in the nozzle shape occur. In response to this, a nozzle forming method which employs wet etching of silicon monocrystal makes it possible to manufacture nozzles of high accuracy, but due to problems of the crystalline structure, nozzles having a quadrangular planar shape are formed (see Japanese Patent Application Publication No. 56-135075).
Furthermore, in a normal inkjet recording apparatus, ink is pushed out from the inkjet head at periodic intervals as a countermeasure to head blockages, and wiping is carried out in order to clean the nozzle surface of the head (Japanese Patent Application Publication No. 5-293973).
However, in the case of square nozzles which are formed using wet etching of silicon monocrystal, ink is liable to spill over from the corner portions when wiping, and deviation of the flight of the ink occurs with a certain probability in nozzles where ink has spilled and in nozzles where the spilled ink has become attached. Furthermore, since dirt is liable to gather in the corner portions of nozzles which have a planar shape including corners, then the nozzle shape becomes asymmetrical due to dirt which collects in the corner portions, and ejection abnormalities such as deviation of the direction of ejection and ejection failures, and the like, are liable to occur. There has been no effective maintenance method for high-precision nozzles formed by wet etching of silicon which has resolved these problems.
FIG. 19A is a plan diagram illustrating an enlarged view of a portion of a nozzle surface 202A of an inkjet head (head) 202 with a nozzle 200 having a substantially square planar shape. As illustrated in FIG. 19A a plurality of nozzles 200 are disposed in a matrix configuration in the nozzle surface 202A of the head 202. When the nozzle surface 202A of the head 202 illustrated in FIG. 19A is wiped with a blade 204, if wiping is performed following the diagonal direction of the nozzles (as indicated by the arrow in FIG. 19A), then dirt is liable to collect in the corner portions 200A of the nozzles 200 as described above.
FIG. 19B illustrates a schematic view of the state of the nozzle surface 202A after the completion of wiping. As illustrated in FIG. 19B, ink droplets 206 and dirt 208 drawn out from the corner portions 200A of the nozzles 200 adhere to the nozzle surface. Adhering matter of this kind on the nozzle surface 202A may affect the ink ejection characteristics and give rise to ejection abnormalities.